The introduction of computer networks and personal computing has forever changed users' expectations of what computer systems can accomplish. Individual users no longer expect to travel to a particular location to have their processing needs met. Instead, individuals expect to have sufficient computing power sitting on their desk to get the job done; or, at least, to have their personal computers networked to sufficient resources remote from their location to accomplish the task.
Attempts have been made to improve the "user-friendliness" of such personal computers, including the development of "window" systems to give users the illusion of working from their desktop electronically. This metaphor suffers, however, from the size limitation of the usual monitor screen for personal computers--no one would ever think of using an actual desktop only nine inches high by eleven inches wide. Personal computers remain static objects commanding the attention of users.
The notion of a computing environment in which computers themselves disappear into the background was raised by Mark Weiser, "The Computer for the 21st Century," Scientific American, September 1991. Two issues of crucial importance to transmission and display of information in such a "ubiquitous" computing environment are location and number of devices.
Weiser postulates a world in which there are many computing and computer-controlled devices surrounding each user all the time. In one example of such a system, he describes devices ranging from small computational devices called "Tabs"--.-inch-scale computers which are networked via wireless links--to yard-scale displays that may be used as electronic blackboards called "Board," that may cover the entire wall of a room.
Users may also wear "Active Badges," credit-card-sized devices that emit an infrared identification signal that can be sensed by receivers placed in each room of a building, thereby allowing detection of where each user is currently located. Active Badges can also be attached to other moving objects, such as portable printers and copiers.
Also discussed by Weiser at page 99 are "Pads," scrap-paper-like, notebook-sized computers that have no individualized identity or ownership. Weiser postulates that in the future there will be many Tabs and Pads per person, just as today there are many paper notebooks and stick-on notes per person. Consequently, users will interact with many different devices, both serially and in parallel, during the course of their daily lives.
"Guest" Tabs or Badges, and "scrap" Pads are devices not owned by any particular user. Instead, they are available--perhaps at the entrance to a building in the case of guest Badges, or in meeting rooms in the case of Tabs and Pads--for use by whoever picks them up. Picking up an Active Badge might involve checking it out from building security so that its association with a particular user can be registered with the system.
In the environment described in Weiser, specific actions may be taken by computers based on knowledge of location. For example, a Board may be configured as a public information bulletin board, its display information attuned to the people reading it. Room audio amplification or lighting may be controlled according to the desires of the people using Tabs or Pads in the room at that moment. Remote actions may be triggered by a user's presence at a location, such as a login procedure started when a user enters his or her office.
Jock Friedly, in "The Office of the 21st Century," Palo Alto Weekly, May 6, 1992, further describes a ubiquitous computing environment including Tabs and Active Badges which broadcast signals that may be tracked throughout the computing environment. Badges indicate where a person is so that phone calls, for example, may be forwarded to a user's location.
In a ubiquitous computing environment such as described by Weiser, users may further desire different automatic actions to be made by the system based on the context surrounding them. Some actions should only take place under controlled conditions. The environment or context of a user may affect operations the user might wish nearby computing systems to perform. For example, a user in a private meeting may not wish to have phone calls forwarded to that location. A message that is private may be displayed on a user's private Pad, but probably not on a public Board.
Similarly, a particular computing device may respond to users in different ways depending on the environment and context. For example, if one user walks into an unoccupied room, each computing device in that room may temporarily assign some measure of ownership control of itself or its resources to that user. When a second user enters the same room some, all, or none of the computing devices may allow the second user ownership rights, depending on the context and environment.
As described in Weiser, a user may be able to migrate any window that may appear on a workstation screen onto a Tab, Pad or Board. This allows users ongoing use of different I/O devices to interact with their electronic data and applications. Which devices will be used will depend on the circumstances of the user. In addition, more than one device might be used to interact with the system at the same time. For example, a user might keep several Pads on his or her desk, and migrate "secondary" applications, such as system status monitors, from a workstation screen onto those Pads. This would free up the workstation screen for use by "primary" applications, such as word processors and spread sheets. Just as today people spread out papers across their entire desks, so too might the user of tomorrow spread out work onto multiple electronic screens, be they Tabs, Pads, Boards, or workstations.
When a user goes to a meeting in another room, the user may take along one of those screens, or may choose to migrate the contents of one or more screens onto the I/O devices available in the meeting room, such as a Board, or one of several scrap Pads in the room.
Such a ubiquitous environment should enable users to make better use of their time and space. For example, some methods users employ to remind themselves of events--notes, pagers, beeping wristwatches, electronic calendars--cannot support automatic message delivery to a remote system, and cannot issue special messages tailored to the physical location and environment of the particular user.
Although there may be several ways to support a "ubiquitous computing" environment to accommodate the entire range of mobility required for ubiquitous computers, a preferred implementation is a network that allows "wireless" communication with mobile devices. To date, many "wireless" networks have already been designed--the most notable, perhaps, being the cellular telephone network. Wireless network systems are generally concerned with the physical layer of the network, and more specifically, with methods of transferring the communication support for a mobile unit from one base station to another. These issues may be classified as problems in "communication continuity." Communication continuity is concerned primarily with mechanisms for providing a continuous pathway for data between two or more units, at least one such unit being mobile, and for reestablishing a data pathway in the event of an unwanted disruption. By contrast, "processing continuity" relates to maintaining a current and proper processing context between two units.
A system for maintaining communication and processing continuity between a mobile processing unit and remotely resident applications is described in coassigned, copending patent application 08/100,655 entitled A METHOD AND SYSTEM FOR MAINTAINING PROCESSING CONTINUITY TO MOBILE COMPUTERS IN A WIRELESS NETWORK, filed Aug. 30, 1993 by Want et al., incorporated herein by reference. The system includes a network backbone, at least one stationary processor coupled to the backbone, and at least one transceiver coupled to the backbone. The transceivers are configured to communicate with the mobile unit through a wireless medium. Mobile units intermittently communicate with applications. The system employs a process that is dedicated to handling all communications between its associated mobile unit and applications. This process is responsible for the scheduling of communications sessions with the mobile unit.
One aspect of the present invention is the ability to provide a system in which actions of the system are initiated or triggered based on the context (for example, the location of the user or other users, the time of day) and the environment (for example, the user's location, nearby computing devices available) in proximity to the user.
Another aspect of the present invention provides a system in which the delivery of electronic messages to a particular user or users may be selective, depending upon the context or state of the user or users. Furthermore, appropriate computing devices for particular actions, such as delivery of electronic messages, are selected based on the environment in proximity to the user in relation to the properties of the message.
In order to carry out these and other related functions, the system may have knowledge not only of users, machines, and computing devices, but of the context and environment that the users and devices are operating in. The system may know, for example, the physical location of a user, what computing devices are available at that location, what other users may be in close proximity to the user. The system may further provide processing continuity over a range of locations. For particular operations, the system may be able to discern predefined control variables, and may be sensitive to the context of certain actions.